Field of the Invention
The present invention relates to a detection apparatus, a measurement apparatus, an lithography apparatus, and a method of manufacturing an article.
Description of the Related Art
A detection apparatus which causes light to be obliquely incident on a substrate and detects the height of the substrate using light reflected by the substrate may detect the height of a substrate where a plurality of layers having different refractive indices are overlapped, such as a substrate where a resist layer is formed on an Si layer. In this case, light reflected by the surface of the top layer out of the plurality of layers and light reflected by the interface between the top layer and its underlying layer are incident on the light receiving device of the detection apparatus. Therefore, when detecting the height of the substrate using the light reflected by the interface, the light reflected by the surface of the top layer may become a noise component and a detection error may be generated. That is, in order to detect the height of the substrate accurately by reducing the detection error, the intensity difference between the light reflected by the interface and the light reflected by the surface of the top layer is preferably maximized. Japanese Patent No. 3139023 has proposed a method of reducing the light reflected by the surface of the top layer by causing p-polarized light to be incident on a substrate at the Brewster's angle.
P-polarized light is not reflected by the surface of the top layer on the substrate if it is incident on the substrate at the Brewster's angle as in the method described in Japanese Patent No. 3139023. It is therefore possible to detect the height of the substrate using only p-polarized light reflected by the interface. It is extremely difficult, however, to extract only p-polarized light by removing s-polarized light completely from light. Therefore, even in the method described in Japanese Patent No. 3139023, the detection error may also be generated when s-polarized light is reflected by the surface of the top layer on the substrate.